Which Tow Vehicle

Dan G wrote:
Crash-worthiness and energy absorbtion is ENTIRELY down to design, not
material.

The major glider manufacturers don't agree with this: take look at the
cockpit of a Schleicher glider, for example, and see how little of it is
carbon fiber. Aramids and glass fiber absorb energy better than carbon
fiber, and so a designer will use them if it is possible.

Nonetheless, it is wrong to claim (as did Tom G) that a steel structure
is always better than one of aluminum or composite, as the design can
compensate for properties of the other materials.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Oct 11, 3:41 pm, Eric Greenwell wrote:
Dan G wrote:

Crash-worthiness and energy absorbtion is ENTIRELY down to design, not

material.

The major glider manufacturers don't agree with this: take look at the
cockpit of a Schleicher glider, for example, and see how little of it is
carbon fiber. Aramids and glass fiber absorb energy better than carbon
fiber, and so a designer will use them if it is possible.

Didn't I say it's design, not material? :-) However Shleicher do
actually use carbon fibre reinforcements on at least some of their
cockpits - check their website:

http://www.alexander-schleicher.de/p...g29_main_e.htm

Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.


Dan

Dan G wrote:
On Oct 11, 3:41 pm, Eric Greenwell wrote:
Dan G wrote:

Crash-worthiness and energy absorbtion is ENTIRELY down to design, not

material.
The major glider manufacturers don't agree with this: take look at the
cockpit of a Schleicher glider, for example, and see how little of it is
carbon fiber. Aramids and glass fiber absorb energy better than carbon
fiber, and so a designer will use them if it is possible.

Didn't I say it's design, not material? :-) However Shleicher do
actually use carbon fibre reinforcements on at least some of their
cockpits - check their website:

http://www.alexander-schleicher.de/p...g29_main_e.htm

All Schleicher gliders, beginning with the ASW 24, use carbon fiber
rails on the cockpit sill, but even on the ASG 29, most of the cockpit
structure is still glass fiber and aramid composite. Gerhard Waibel had
an excellent article describing the design of the ASW 24 cockpit,
considered the first of the modern "safety cockpits", in Soaring
Magazine about 20 years ago, and also more recent articles in Technical
Soaring. Those articles can explain the design of an improved cockpit
much better than I can here.


Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

Lange does use a crush zone, and it certainly did not
require "several feet longer fuselage" for Antares. See:
http://www.lange-flugzeugbau.de/htm/...0e/safety.html
The crushable nose-cone is a separate part from the
remainder of the safety cockpit, attached late in the
manufacturing. I'll try get some pictures on my
web site...

See ya, Dave "YO"

wrote:

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

Lange does use a crush zone, and it certainly did not
require "several feet longer fuselage" for Antares. See:
http://www.lange-flugzeugbau.de/htm/...0e/safety.html
The crushable nose-cone is a separate part from the
remainder of the safety cockpit, attached late in the
manufacturing.

It looks like a good design; still, an additional 4" over a "normal"
fuselage is not much compared to the several feet of crush zone
available in an automobile. Is it intended that the cockpit function in
the "safety cell" manner that Dan G was describing, or is it designed to
crumple progressively to absorb energy, like the Schleicher cockpits?

I wish there indpendent tests of glider crash protection that were
released to the public, because it is very difficult for us to determine
the effectiveness of a design, especially new designs that have not had
any crashes yet.

I'll try get some pictures on my
web site...

I'd love to see those.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org